Elevations in ambient particulate matter(PM)air pollution have been associated with increases in hospital admissions and emergency department visits for asthma and other respiratory illnesses, and with excess daily mortality. This study seeks to examine the effects of particulate matter on asthmatics by determining to which components of PM asthmatics are most sensitive, and by what mechanism. Baseline serum and nasal lavage levels of proinflammatory mediators, as well as TH1 and TH2 induced cells, will be identified at low PM and high PM exposure. Epidimiologic data on PM will also be collected and correlated to the asthmatic's symptoms.